| This investigation describes the progression of and potential risk factors for clinical attachment loss (LOA) and tooth loss over 20 years among a group of 455 rural, male Sri Lankan tea laborers aged 14-31 who practiced no preventive oral hygiene and had no access to professional dental care. Kaplan-Meyer survival analysis revealed that tooth mortality: (1) was generally greater in the mandible than the maxilla; (2) exhibited a mirror image loss pattern from left to right sides; (3) was greatest for mandibular molars and least for mandibular canines and (4) increased for all teeth examined over time. Proportional hazards analysis revealed that: (1) missing a molar tooth at baseline carried nearly a 2-fold increased risk of subsequent tooth loss of any kind; (2) there was an 8.5% increased risk of tooth loss for each millimeter increase in difference of LOA at baseline among subjects losing versus not losing a similar tooth and (3) betel nut users at baseline had a 33% reduction in risk of tooth loss compared to non-users. Repeated measures MANOVA revealed that age, calculus (ClI), gingival inflammation (GI), number of missing teeth over time and time were significantly associated with increases in mean LOA over time. Similar analysis for tooth loss revealed significant increases in tooth loss with increased LOA, missing 1+ tooth at baseline and time. In summary, this study revealed that: (1) LOA and tooth loss increased significantly over 20 years; (2) LOA was associated with age, CI, GI, number of missing teeth and time; (3) early loss of molars was predictive of subsequent tooth loss and (4) betel nut use had a significant protective or delaying effect against tooth loss over time. The reason(s) for betel nut's protective effect on tooth loss remains unclear and requires further epidemiologic and laboratory investigation. |
